Between 2-3 yrs, child is usually able to speak 3 word sentences & uses small words. There are individual variations with some delay. But if you are concerned about his development as compared to other children of the same age, then you can discuss about the same with his paediatrician. There are multiple causes which need to be ruled out eg. deafness, mental retardation, autism etc.
Next Steps
Please consult a peadiatrician.